Apparatus for maintaining a vacuum



Aug- 4, 1925.

' G. L. KENNEDY APPARATUS,:FOR MAINTAINING A VACUUI Filed Feb. 25. 1924 tion and accompanying drawings; and

Patented Aug. 4, 1925.

UNITED STATES 1,548,044 PATENT. OFFICE.

GUY L. KENNEDY, OF NEW YORK, N. Y., ASSIGNOR T0 KEN-GRIP CORPORATION, OF NEW YORK, N. Y.

APPARATUS FOR MAINTAINING A VACUUM.

Application filed February 23, 1924. Serial No. 694,792.

To all whom it may concern:

Be it known that I, GUY L. KENNEDY, a citizen of the United States, residing at New York, in the county of Bronx and State of New York, have invented certain new and useful Improvements in Apparatus for Maintaining a Vacuum, of which the following is a specification.

My invention pertains creating and maintaining a vacuum; and has for its object to produce a vacuum and keep the vacuum substantially constant in the midst of influences and conditions that tend to make the vacuum a variable one.

The nature and advantages of my invention will appear from the following descrip I 0 course reservg the right to make any changes in the structure used or manner of proceeding adopted, without departing from the scope and spirit of my invention as the same is defined by the broad meaning of the terms of the appended claims.

On the drawings:

Figure 1 is a diagrammatic view to explain the principle of my invention;and

Figure 2 is a view of a construction by which my invention can be practiced.

The same numerals identify the same parts throughout.

Figure 1 is a longitudinal sectional View through a casing 1, having an inlet valve 2, a permanently open inlet port 3, and a tube 1, mounted in the casing, and closed at one end except for the inlet 3; the other end of the tube being open and being approximately in the middle of the casing. Connected to the tank is an exhaust or suction pump to draw the air out of the casing 1.

Suppose the valve 2 to be closed and for the moment no inlet port 3 to be present. Then with the pump operating one might produce a vacuum equal to say 18 inches of mercury displacement in the vessel or casing 1, that is to say if a manometer or U-shaped tube '1 containing mercury has the upper end of one arm in communication with the casing and the upper end of the other arm open to the atmosphere, the difference of level of the mercury in the two arms will be 18 inches.

If now one opens the air inlet 2 to admit air, the vacuum in the casing 1 drops from 18 inches of mercury displacement to zero in direct ratio with the extent to which the into apparatus forlet 2 is opened. My aim is to create within the casing 1 a point or small space, where the vacuum shall be substantially constantly equal tosay 2 inches of mercury displace-. ment regardless of the degree of vacuum in theremainder of the casing 1. Of course if the valve 2 is small enough or at least partly closed and the pump kept running one may keep in the casing 1 a, vacuum of say 18 inches of mercury displacement, indefinitely, that is the air, in the casing can be extracted by the pump too fast for air coming in through the inlet 2 to obviate this vacuum.

Sup ose nowthe small open air inlet 3 is provi ed, the pump continuing to run and valve 2 being closed as much as necessary. Then inside of the casing 1 will be a small space adjacent the port 3 where the vacuum has dropped to approximately 2 inches of mercury displacement, while still remaining equivalent to 18 inches in the remainder of the casing. If the tube 4 be mounted inside the casing, with one open end substantially at the middle of the casing and the other end open only to the inlet 3, it will be found that, if the vacuum in the casing remains, equivalent to 18 inches of mercury displacement, the vacuum in tube 1 will be substantially constantly equal. to 2 inches of mercury displacement.

If now inlet 2 be again opened enough to admit airinto the casing 1, the vacuum in the casing will drop with the opening of inlet 2 more and more, as has been shown, to

zero. Then the vacuum in tube 4 must also 1 drop to zero but it does not begin to drop until the vacuum in the casing has dropped to about 2 inches of mercury displacement.

It is evident, therefore, that this simple device will maintain a substantially constant vacuum within tube 1 until the vacuum in the casing 1 falls below 2 inches of mercury displacement; and that from this point down to zero, the vacuum in the tube 4: is subject to the same variation as the vacuum in the casing.

If, then, one is to establish say a 2 inch Vacuum within tube 1, such that it Will remain constantly at 2 inches of mercury displacement, plainly some means must be found to increase the vacuum within tube 4, after or at the instant the vacuum in the casing 1 drops to 2 inches.

This end is gained by the construction shown in Figure 2. The casing 1 is utilized as before with a pump to exhaust air from the interior thereof. Mounted inside the casing is a tube t, communicating with theatmosphere outside the casing through a small open port 3. Surrounding the tube inside the casing is a larger tube 5, and 6 are inlet ports in the wall oi the casing leading to the annular space between the tubes 4 and 5. The inner end of this space inside the casing is closed by the cone-shaped ring valve 2 which rests against the ends of the tubes 5 and 6. Guide rods 7 are affixed to this valve and pass through to the outside of the casing where they terminate in heads 8 between which and the exterior of the casing are springs 9 to hold the valve 2 normally against the inner extremities of the tubular elements 4: and 5, and close the space between the tubes 4; and 5.

Now with the pump running, and a vacuum'of 18 inches of mercury displacement in the casing, a vacuum of 2 inches of mercury displacement will exist in the tube 4 adjacent the inlet 3. If the valve 2 is caused or allowed by any means or in any manner to lift or open, as by mechanical means pushing against the heads 8 of the rods 7 to overcome the springs 9 and thus open the valve 2* more or less, with resultant variation of pressure conditions to change the vacuum in the casing 1, the vacuum in the casing will drop because air flows in through the ports 6, the same as through the valve 2 in Figure 1, and through the annular space between the tubes 4 and 5 past the inner ends of these tubes. The flow of air past the inner end of the tube t has an aspirating action on this tube, and as a result the vacuum in this tube remains substantially constant and equal to about 2 inches of mercury displacement at least in proximity to the small port 3, even when the vacuum in the rest of the casing 1 falls to zero. This fact has been established by repeated laboratory tests. Hence I obtain a substantially constant degree of vacuum in the tube 4, in spite of conditions or influences tending to lower or entirely obliterate the vacuum in the remaining part of the casing 1.

The substantially constant vacuum can be produced as above described with either air or liquid or both admitted by way of inlet 3, provided the liquid is such as to volatilize quickly in the element 4.

Having described my invention, what I believe to be new and desire to secure and protect by Letters Patent of the United States is 1. A device for producing and maintaining a substantially constant vacuum comprising a casing through which a gaseous medium is passed, the interior of said casing having an enclosed space with an outlet de livering to said medium and with an inlet communicating with the exterior of said casing, said medium exerting an aspirating action on the said space and creating and maintaining a substantially constant vacuum therein.

2. A device for producing and maintaining a substantially constant vacuum comprising a casing through which a gaseous medium under conditions of varying pressure is passed, said casing having an enclosed space with an outlet delivering to said medium, and an inlet of pre-determined area communicating with the exterior of said casing, said medium exerting an as pirating action at said outlet and creating and maintaining a substantially constant vacuum in said space, and means for regulating the volume of said medium flowing adjacent said outlet.

3. A device for producing and maintaining a constant vacuum, comprising a vessel from which the contents are drawn, said vessel having a relatively small open inlet, a hollow element to which said inlet leads, a second hollow element surrounding the first element, the space between said elements communicating at one end with the outside 01 said vessel, and a valve to control said space, said valve when open permitting a flow through said space past the inner end of the first elements to maintain the degree of vacuum therein.

In testimony whereof I my signature.

GUY L. KENNEDY. 

